Production of artificial protein filaments



Patented Apr. 18, 1950 2,504,844 PRODUCTION or' ariri'rrcm l rrto'rnm FmAM n'rs James F. Keggin, West K i lbride, Scotland, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing.

Application May 29, 1946, Serial No. 673,170. In Great Britain June 20, 1945 4 Claims.

The present invention relates to the production of high tensile artificial protein filaments. More particularly, it is concerned with the treatment of protein filaments produced by wet spinning of aqueous protein solutions which have been rendered resistant to attack by boiling water and hot dilute acids, for example, by immersion in a strongly acidified saline formaldehyde solution, in order to increase the tensile strength thereof.

The invention is especially applicable to such filaments produced from alkaline solutions of casein and alkaline solutions of vegetable globulins, for instance peanut globulin solutions or soya bean globulin solutions in dilute sodium hydroxide solution.

The object of the present invention is to increase the strength per unit cross-sectional area of the filaments of the kind herein specified.

According to the present invention th method for the production of improved artificial protein filaments from filaments of the kind herein specifled comprises subjecting the said filaments in air dry state, and preferably at a relative humidity of above 30 per cent, to sufficient tension to stretch them beyond their elastic limit but insufficient to break them, and then releasing the tension on the thus extended filaments.

The improved protein filaments thus produced can be cut into staple fibre form and the staple fibre may be treated if desired with an aqueous formaldehyde solution.

The invention is illustrated by the following example:-

Example A matured alkaline solution of peanut globulins is spun into a coagulating bath consisting of an aqueous solution containing 1.5 per cent sulphuric acid and 20 per cent sodium sulphate at 30 C. from which it is withdrawn at a linear rate exceeding the linear rate of extrusion and the coagulated filaments are stretched in a bath of the same composition. They are then wound on to a swift and immersed in a saturated sodium chloride solution at 30 C. for 10 minutes and then in twenty times their dry weight of a bath consisting of a solution containing 2.5 per cent sulphuric acid, 1.5 per cent formaldehyde and 26 per cent sodium chloride for 20 hours at 40 C. The resulting filaments are then thoroughly washed with water and soaked in an 0.06 per cent solution of sodium cetyl sulphate and then in 0.5 per cent sodium carbonate solution. They are then thoroughly washed in water and dried at 100 C. The resulting filaments have an average strength of 7.1 kilograms per square millimetre. They are practically unaffected in handle by treatment for 90 minutes at 97 C. in a bath containing 0.1 per cent sulphuric acid and 0.25 per cent sodium sulphate, and the bath liquor fails to give a positive response to the so-called biuret test for protein degradation products.

These filaments conditioned in air are then gradually stretched to about 1.5 times their original length at 20 C. and at a relative humidity of i. above 30 per cent by the application of a gradually increasing tension until the filaments extend plastically, when upon release of this tension the filaments do not retract.

The filaments now have an average strength of 10.5 kilograms per square millimetre. The filaments thus produced can be immersed in a strong aqueous formaldehyde solution having a pH between approximately 9.0 and 10.0 or 2.0 and 3.5 for a short period of time in order to further improve their physical and chemical properties.

I claim:

1. The method for the production of relatively high tensile strength artificial protein filaments from protein filaments which have been rendered resistant to attack by boiling water and hot dilute acids, which comprises subjecting said filaments in an air-dry state to sufficient tension to stretch them beyond their elastic limit, but insufficient to break them, and then releasing the tension on the thus extended filaments.

2. The method as claimed in claim 1, wherein the stretching is conducted in an atmosphere having a relative humidity of above 30 percent.

3. The method as claimed in claim 1, wherein said filaments are made of peanut protein.

4. The method of producing artificial protein filaments of relatively high tensile strength which comprises wet spinning a matured alkaline solution of a vegetable globulin into an acidic saline 1 coagulating bath, stretching the resulting filaments, rendering the filaments resistant to attack by boilin water and hot dilute acids by immersion in an acidic, saline formaldehyde solution, washing the filaments, drying the filaments, and, thereafter, stretching the dried filaments in an 3 atmosphere of relative humidity above 30 percent by application of gradually increasing tension until the filaments stretch beyond their elastic limit, but less than necessary to break them, and then releasing the tension upon the extended filaments.

JAMES F. KEGGIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,603,080 Hirasawa Oct. 12, 1926 2,103,218 Gwaltney et a1 Dec. 21, 1937 2,220,958 Jennings Nov. 12, 1940 OTHER REFERENCES Artificial Fibers from corpuscular and Fibrous Proteins, Lundgren and O'Connell Industrial and Engineering Chemistry, pages 370-374, April 1944.

Textile World, September 1945, Synthetic A vFibers charts, pages 117-132. (Copy in Division 

4. THE METHOD OF PRODUCING ARTIFICAL PROTEIN FILAMENTS OF RELATIVELY HIGH TENSIL STRENGTH WHICH COMPRISES WET SPINNING A MATURED ALKALINE SOLUTION OF A VEGETABLE GLOBULIN INTO A ACIDIC SALINE COAGULATING BATH, STRETCHING THE RESULTING FILAMENTS, RENDERING THE FILAMENTS, RESISTANT TO ATTACK BY BOILING WATER AND HOT DILUTE ACIDS BY IMMERSION IN AN ACIDIC, SALINE FORMALDEHYDE SOLUTION, WASHINGTON THE FILAMENTS, DRYING THE FILAMENTS, AND, THEREAFTER, STRETCHING THE DRIED FILAMENTS IN AN ATMOSPHERE OF RELATIVE HUMIDITY ABOVE 30 PERCENT BY APPLICATION OF GRADUALLY INCREADING TENSION UNTIL THE FILAMENTS STRETCH BEYOND THEIR ELASTIC LIMIT, BUT LESS THAN NECESSARY TO BREAK THEM, AND THEN RELEASING THE TENSION UPON THE EXTENDED FILAMENTS. 